网站停机时会抛出哪个异常？

Question

我正在使用jsoup从网站上刮取数据。我想知道当我从哪里抓取数据的网站关闭时会抛出哪个异常。
是SocketException还是NoHttpResponseException或其他？
我看到NoHttpResponseException在服务器收到请求但没有响应时抛出，这是正确的吗？

Answer 1

我测试了我们自己的网站，我取下来的Tomcat我得到以下java.net.SocketTimeoutException后：

java.net.SocketTimeoutException: connect timed out 
    at java.net.DualStackPlainSocketImpl.waitForConnect(Native Method) 
    at java.net.DualStackPlainSocketImpl.socketConnect(DualStackPlainSocketImpl.java:85) 
    at java.net.AbstractPlainSocketImpl.doConnect(AbstractPlainSocketImpl.java:350) 
    at java.net.AbstractPlainSocketImpl.connectToAddress(AbstractPlainSocketImpl.java:206) 
    at java.net.AbstractPlainSocketImpl.connect(AbstractPlainSocketImpl.java:188) 
    at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:172) 
    at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:392) 
    at java.net.Socket.connect(Socket.java:589) 
    at sun.security.ssl.SSLSocketImpl.connect(SSLSocketImpl.java:668) 
    at sun.net.NetworkClient.doConnect(NetworkClient.java:175) 
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:432) 
    at sun.net.www.http.HttpClient.openServer(HttpClient.java:527) 
    at sun.net.www.protocol.https.HttpsClient.<init>(HttpsClient.java:264) 
    at sun.net.www.protocol.https.HttpsClient.New(HttpsClient.java:367) 
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.getNewHttpClient(AbstractDelegateHttpsURLConnection.java:191) 
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect0(HttpURLConnection.java:1138) 
    at sun.net.www.protocol.http.HttpURLConnection.plainConnect(HttpURLConnection.java:1032) 
    at sun.net.www.protocol.https.AbstractDelegateHttpsURLConnection.connect(AbstractDelegateHttpsURLConnection.java:177) 
    at sun.net.www.protocol.https.HttpsURLConnectionImpl.connect(HttpsURLConnectionImpl.java:153) 
    at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:563) 
    at org.jsoup.helper.HttpConnection$Response.execute(HttpConnection.java:540) 
    at org.jsoup.helper.HttpConnection.execute(HttpConnection.java:227) 
    at org.jsoup.helper.HttpConnection.get(HttpConnection.java:216) 
    at testing.Test.main(Test.java:19) 

这是我使用的代码：

public static void main(String[] args) { 
    try { 
     Document document = Jsoup.connect("https://example/folder").validateTLSCertificates(false).timeout(1000).get(); 
     System.out.println(document); 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 
} 

NoHttpResponseException似乎是一个Apache的HttpClient例外（org.apache.commons.httpclient.NoHttpResponseException）。由于Jsoup没有apache依赖关系，因此SocketTimeoutException可能是答案。